The physical origin of dusty winds in highly accreting AGN

Abstract

Active galactic nuclei (AGN), super-massive and accreting black holes at the centres of galaxies, are some of the most luminous objects in the Universe. Their internal structure is complex and driven by fundamental AGN parameters, such as the accretion rate. However, due to the compact size of AGN, spatially resolved studies of these structures are difficult. In this work, I investigate specifically the physical origins of dusty winds in highly accreting AGN using high angular resolution techniques to resolve the central parsec. I explore the behaviour of the dusty winds, the wind launching region, and the accretion disk, which drives the dusty winds. To observe the dust, I used optical interferometry, and especially the mid-infrared instrument MATISSE, for which I developed a new data reduction method for faint objects. I published the first LM-band measurements for Type 1 AGN: the highly accreting objects I Zw 1 and H0557-385, in which the wind launching region has been resolved. For the super-Eddington AGN I Zw 1, I also resolved the accretion disk using reverberation mapping with a sub-daily cadence in seven photometric bands (uBgVriz_s). Combining my results with archival observations, I constructed the directly measured size-wavelength relation between 3 - 13 μm for H0557-385 and 3000 Å - 13 μm for I Zw 1. These relations show several things about highly accreting AGN: firstly, the accretion rate appears to increase the opening angle of the dusty wind such that it is in a preferentially equatorially orientated direction. Secondly, we are directly observing the dusty wind launching region and an inner puffed-up dusty disk for the first time. The accretion disk, however, does not seem to vary noticeably from those in sub-Eddington AGN. The accretion rate does drive AGN structure, particularly in the dusty torus, but the effects vary across the different components studied here. In the future, lower sensitivity limits of optical interferometric instruments will increase the sample size of observable objects considerably and allow for a deeper understanding of internal AGN structure evolution with AGN parameters.

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Identifiers

ORCID for Farin Drewes: orcid.org/0000-0001-6039-1988

ORCID for Poshak Gandhi: orcid.org/0000-0003-3105-2615

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